Access to a shared memory region on a thread-level basis may be implemented using Translation Lookaside Buffers (TLBs). The process of changing which threads can access the shared memory region is facilitated using time-consuming TLB shoot-downs. Through alternate uses of a private context ID register in some systems, TLB shoot-downs may be reduced. Similarly, in other systems, alternate uses of a current page table register may also reduce TLB shoot-downs.